Stub having an optical fiber

ABSTRACT

A device includes a stub, and an optical fiber. The stub has an aperture, and a first end and a second end. The optical fiber is mounted in the aperture of the stub. The optical fiber has a first end and a second end. The first end of the optical fiber is polished so as to be flush with the first end of the stub. The second end of the optical fiber is cleaved at a predetermined position so as to provide for a predetermined length of the optical fiber measured from the first end of the optical fiber to the second end of the optical fiber.

This is a division of U.S. patent application Ser. No. 10/151,362, nowU.S. Pat. No. 6,805,491, filed May 20, 2002, which is herebyincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention pertains to the field of fiber optics. Theinvention more particularly concerns an optical fiber mounted in a stubwhere one end of the optical fiber is cleaved and the other end of theoptical fiber is polished. Glass material is used to construct theoptical fiber or waveguide.

2. Discussion of the Background

Cleaving an optical fiber by mechanical means is known in the art andcleaving with a laser or cutting beam is also known in the art and isdisclosed in U.S. Pat. Nos. 4,710,605, and 6,139,196. U.S. Pat. Nos.4,710,605, and 6,139,196 are hereby incorporated herein by reference.U.S. Pat. No. 4,710,605 discloses a single optical fiber mounted in afixture where the laser cleaves a bare optical fiber. U.S. Pat. No.6,139,196 discloses a single optical fiber, including a fiber jacketsurrounding the optical fiber, mounted in a fixture where the lasercleaves the fiber jacket and the optical fiber. In both cases, thecleaved optical fibers are then removed from their respective fixturesfor further processing.

Additionally, forming a lens at an end of an optical fiber with a laseris known in the art and is disclosed in U.S. Pat. Nos. 4,932,989;5,011,254; and 5,256,851. U.S. Pat. Nos. 4,932,989; 5,011,254; and5,256,851 are hereby incorporated herein by reference. U.S. Pat. No.4,932,989 discloses a single optical fiber mounted in a fixture, wherethe optical fiber has a tapered lens formed at an end of the opticalfiber with a laser. U.S. Pat. No. 5,011,254 discloses a single opticalfiber mounted in a fixture, where the optical fiber has a hyperboliclens formed at an end of the optical fiber with a laser. U.S. Pat. No.5,256,851 discloses a single optical fiber mounted in a fixture, wherethe optical fiber has an asymmetric hyperbolic lens formed at an end ofthe optical fiber with a laser. In all three cases, the cleaved andlensed optical fibers are then removed from their respective fixturesfor further processing.

Typically, the cleaved and lensed optical fiber is mounted in a housingwhich contains either an optoelectronic transmitter or an optoelectronicreceiver. In the case of the optoelectronic transmitter, theoptoelectronic transmitter emits a light signal which shines on the lensof the optical fiber where the light signal is efficiently introducedinto the optical fiber. In the case of the optoelectronic receiver, alight signal propagates along a length of the optical fiber and exitsthe optical fiber, thus focusing the light signal, in an efficientmanner, on the optoelectronic receiver.

Both the cleaving step and the lensing step of the prior art requirenumerous time consuming set-up operations, low yields, and result indifficulty in handling and placing the optical fiber in an assembly.

SUMMARY OF THE INVENTION

Therefore, it is an object of the invention to provide a device which iseasily assembled into other structures or housings.

It is another object of the present invention to provide a terminatedoptical fiber which includes a stub attached to the optical fiber whichprovides for shorter set-up times and thus increased productivity.

It is yet another object of the present invention to provide a cleavedand lensed optical fiber which is robust and rugged enough not to bedamaged by a vibrating feeding machine which is part of an assembly lineprocess to feed the device to another structure for assembly.

In one form of the invention, the device includes a stub, and an opticalfiber, the stub having an aperture, and a first end and a second end.The optical fiber is mounted in the aperture of the stub. The opticalfiber has a first end and a second end. The first end of the opticalfiber is polished so as to be flush with the first end of the stub. Thepolished end is in conformity with the physical contact surface finishstandard. The second end of the optical fiber is terminated at apredetermined position so as to provide for a predetermined length ofthe optical fiber measured from the first end of the optical fiber tothe second end of the optical fiber.

In yet another form of the invention, the device includes a stub, anadhesive material, and an optical fiber, the stub having an aperture,and a first end and a second end. The optical fiber is attached to theaperture of the stub by way of the adhesive material. The optical fiberhas a first end and a second end. The first end of the optical fiber ispolished so as to be flush with the first end of the stub. The polishedend is in conformity with the physical contact surface finish standard.The second end of the optical fiber is cleaved at a predeterminedposition so as to provide for a predetermined length of the opticalfiber measured from the first end of the optical fiber to the second endof the optical fiber.

In still yet another form of the invention, a method is set forth forproducing the first above-described device. The method includes thesteps of selecting a stub having an aperture; forming a portion of theaperture to have a conical shape near the second end of the stub, andwherein the conical shape has an apex; inserting the optical fiber intothe aperture of the stub; polishing a first end of the stub and a firstend of the optical fiber so as to form a physical contact surfacefinish; selecting a location for a second end of the optical fiberadjacent the apex of the conical portion of the aperture of the stub;terminating the optical fiber so as to form a second end of the opticalfiber; and sizing the portion of the aperture having the conical shapeso as to prevent light energy emanating from the second end of theoptical fiber from impinging on a surface of the portion of the aperturehaving the conical shape. Additionally, the stub has a first end and asecond end, and the first end of the stub is separated from the secondend of the stub by a first stub length. Furthermore, the first end ofthe optical fiber is separated from the second end of the optical fiberby a first optical fiber length, and wherein the first stub length isgreater then the first optical fiber length.

In another form of the invention, a method is set forth for producingthe second above-described device. The method includes the steps ofselecting a stub having an aperture; forming a portion of the apertureto have a conical shape near the second end of the stub, and wherein theconical shape has an apex; applying an adhesive material to at least oneof the aperture of the stub and optical fiber; inserting the opticalfiber into the aperture of the stub so as to affix the optical fiber tothe stub by way of the adhesive material; polishing a first end of thestub and a first end of the optical fiber so as to form a physicalcontact surface finish; selecting a location for a second end of theoptical fiber adjacent the apex of the conical portion of the apertureof the stub; cleaving the optical fiber so as to form a second end ofthe optical fiber; and sizing the portion of the aperture having theconical shape so as to prevent light energy emanating from the secondend of the optical fiber from impinging on a surface of the portion ofthe aperture having the conical shape. Additionally, the stub has afirst end and a second end, and the first end of the stub is separatedfrom the second end of the stub by a first stub length. Furthermore, thefirst end of the optical fiber is separated from the second end of theoptical fiber by a first optical fiber length, and wherein the firststub length is greater then the first optical fiber length.

Thus, the device of the invention is superior to existing solutionssince the stub having the optical fiber is connectorized. The device canbe assembled in large quantities and stored. The device can be assembledinto a housing containing an optoelectronic device or it can beassembled onto a board which has unfinished or un-connectorized opticalfiber which need to be terminated. Thus, the device of the invention ismore cost effective than prior art devices.

BRIEF DESCRIPTION OF THE FIGURES

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIG. 1 is a plan view of the device including the stub and the opticalfiber;

FIG. 2 is a plan view of an end of the device of FIG. 1;

FIG. 3 is a cross-sectional view of the device of FIG. 1;

FIG. 4 is a cross-sectional view of another embodiment of the device;

FIG. 5 is a cross-sectional view of the device of FIG. 4 mounted in ahousing along with an optoelectronic device and a separate focusinglens;

FIG. 6 is a cross-sectional view of another embodiment of the devicehaving a lens formed on an end of the optical fiber;

FIG. 7 is a cross-sectional view of the device of FIG. 6 mounted in ahousing along with an optoelectronic device; and

FIG. 8 is a cross-sectional view of another embodiment of the devicehaving the optical fiber housed within the stub.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

Referring now to the drawings, wherein like reference numerals designateidentical or corresponding parts throughout the several views, and moreparticularly to FIGS. 1-3 thereof, is a device 10 including a stub 20and an optical fiber 30.

FIG. 1 is a plan view of the device 10 which includes the stub 20, andthe optical fiber 30. The stub 20 includes a first end 22, and a secondend 24. The optical fiber 30 includes a first end 32, and a second end34.

FIG. 2 is a plan view of an end of the device 10 showing the profile ofthe cylindrically shaped surface 26 of the stub 20. Also shown is theaperture 21 of the stub 20.

FIG. 3 is a cross-sectional view of the device 10 of FIG. 1. The firstend 32 of the optical fiber 30 is polished so as to be flush with thefirst end 22 of the stub 20. The first end 22 of the stub 20 and thefirst end 32 of the optical fiber 30 are polished so as to be inconformity with the physical contact (PC) surface finish standard so asto allow the device 10 to mate with an optical connector (not shown).The second end 34 of the optical fiber 30 extends past the second end 24of the stub. The second end 34 of the optical fiber 30 may be at anyangle including angles other than ninety degrees relative to the lengthof the optical fiber 30 as shown in FIG. 3, however, it is typically cutat an angle of six to ten degrees from a direction perpendicular to thelength of the optical fiber 30. The second end 34 of the optical fiber30 extends beyond the second end 24 of the stub 20 by approximatelythree hundred microns and as such the cantilevered portion of theoptical fiber 30 is relatively stiff and essentially does not bend orflex. The overall length L1 of the device is approximately one-halfinch. The second end 24 of the stub 20 can be cut at any angle, however,it is typically cut at an angle of six to ten degrees from a directionperpendicular to the length of the stub 20.

Initially, a stub 20 is selected which includes an appropriate aperture21. The size of the aperture 21 of the stub 20 is based on the size ofthe optical fiber 30. Typically, the diameter of the aperture 21 isgreater than the diameter of the optical fiber 30. During assembly, anoptical fiber 30 has an adhesive material 38 (for reasons of clarity theadhesive material 38 is not shown in FIGS. 3, 4, and 6) applied to itsouter surface. The optical fiber 30, along with the adhesive material38, is introduced into the aperture 21 of the stub 20. At that time,portions of the optical fiber 30 protrude beyond the first and secondends 22, 24 of the stub 20. The adhesive material 38 secures the opticalfiber 30 to the stub 20. Typically, the adhesive material 38 is an epoxymaterial. The first end 32 of the optical fiber 30 and the first end 22of the stub 20 are polished as described above. The polishing creates asurface which conforms to the physical contact standard and may be oneof many standard shapes, such as SC, LC, and etc. The physical contactstandard requires that the first surface 32 of the optical fiber 30contact the optical fiber of the associated connector (not shown). Thephysical contact eliminates air gaps between the surfaces whichcontribute to insertion losses.

The length L1 of the optical fiber 30 and hence the device 10 ispredetermined. Thus, after the first ends 22, 32 are polished the exactlocation for cutting the optical fiber 30 at the second end 34 can bedetermined to achieve the overall length L1. Once the location of thesecond end 34 of the optical fiber is determined a cleaving step isemployed to perform the cut. The cleaving step can be performedmechanically or by lasing.

Mechanical cleaving consists of scoring the surface of the optical fiber30 with a diamond or sapphire tipped tool so as to create a crack on thesurface of the optical fiber 30 at the location of the second end 34.The optical fiber 30 is then stressed, typically by bending, so as topropagate the crack across the diameter of the optical fiber 30.

Laser cleaving consists of ablating a portion of the optical fiber 30 atthe designated position. The laser does not harm the stub 20 material.The stub 20 is typically made of a ceramic material. However, the stub20 can be made of a polymer material or a metallic material.

Compared to polishing, the cleaving process is quick and accurate, andincreases yields, and the length L1 can be controlled.

FIG. 4 is a side view of another embodiment of the device 50 including astub 60, which is similar to the stub 20, and an optical fiber 70. Thesecond end of the optical fiber 70 is under flush with the surface ofthe stub 60. The stub 60 includes a recess 62 which enables the laser orcutting beam to cut the optical fiber 70 below the surface of the stub60.

FIG. 5 is a partial cross-sectional view of an assembly 80 including anoptoelectronic device 90, a can or lid 94, a focusing element 100, suchas a spherical ball lens, a housing 127, and the device 10. The assemblyhas an overall length denoted by L2. The assembly 80 includes a ferrulereceiving bore 82 for receiving a ferrule of an optical connector whichphysically contacts the device 10. The optoelectronic device 80 and thedevice 10 (including the stub 20 and the optical fiber 30) are attachedto the housing 127. If the optoelectronic device 90 is a transmitter,optical energy flows out of the optoelectronic device 90 and flows intothe focusing element 100 along optical axis 102. The focusing element100 focuses the optical energy on the cleaved end of the optical fiberof the device 10 along the optical axis 103. The optical energy thenflows through the optical fiber of the device 10 and then enters theoptical connector at the first end of the device 10 along optical axis101. If the optoelectronic device is a receiver, then the processdescribed above is reversed. The flow of energy into or out of theoptoelectronic device occurs through an optically active portion of theoptoelectronic device. The cap or lid 94 hermetically seals theoptoelectronic device 90 away from harmful environmental conditions.

In another variation of the invention, FIG. 6 is a cross-sectional viewof the device 10 of FIGS. 1-3 having a lens 36 formed on the second endof the optical fiber 30. The lens can be formed by selectively applyingthe energy of a laser beam to the tip of the optical fiber so as toshape the end. Such a lens 36 eliminates the need for a separatefocusing element 100 as shown and described in FIG. 5.

FIG. 7 is a partial cross-sectional view of the device 10 as shown inFIG. 6, employed in an assembly 110 having an optoelectronic device 90.The optoelectronic device 90 and the device 10 (including the stub 20and optical fiber 30) are attached to the housing 127. Since the lens 36is formed on the end of the optical fiber, the focusing element 100 asshown in FIG. 5 is not required. Thus, the can or lid 94 of the assembly80 of FIG. 5 can be eliminated. The removal of the can 94 provides for amore compact assembly. The overall length L3 of the assembly 110 is lessthan the overall length L2 of the assembly 80 as shown in FIG. 5. Theremaining structure of the assembly 110 allows for hermeticity.

In yet another variation of the invention, FIG. 8 is a cross-sectionalview of the device 210 having an optical fiber 230 housed within a stub220. The device 210 is similar to the device 50 of FIG. 4. Unlike thedevice 50 of FIG. 4, the device 210 of FIG. 8 has one end of the stub220 terminated in a position which is substantially at an angle ofninety degrees relative to the length of the stub 220. Having theoptical fiber 230 housed within the stub 220 which results in a portionof the stub 220 extending beyond the optical fiber 230 provides for amechanically robust and rigid design. Furthermore, the device 210 allowsfor the adjustment of the end of the optical fiber 230 relative to theoptoelectronic device or relative to a separate focusing element such asa ball lens if one is so provided in the assembly. Such an adjustment isprovided in the manufacture of the device 210.

During manufacture, the device 210 is constructed by selecting a stub220 having an appropriate aperture. An optical fiber 230 is insertedinto the aperture so that the optical fiber 230 extends past both endsof the stub 220. The optical fiber 230 extending past the end of thestub 220 having the conically shaped aperture is either cleaved or hasbeen pre-cleaved prior to insertion and also that end of the opticalfiber 230 can be lensed or can pre-lensed if a lens is so desired. Thenan adhesive is placed on the optical fiber 230 near the portion of theoptical fiber extending past the conically shaped aperture of the stub220. The optical fiber 230 is then moved relative to the stub 220 sothat the end of the optical fiber 230 is situated near the apex of theconical portion of the aperture of the stub 220. Any amount of theoptical fiber 230 extending beyond the other end of the stub 220 ispolished flush with the surface of the stub 220 as described in theprevious embodiments. Depending on the application, the position of theend of the optical fiber 230 near the conically shaped aperture of thestub 220 can be controlled and prescribed relative to the end of thestub 230 located near the conically shaped aperture. Therefore, the endof the optical fiber 230 near the conically shaped aperture ray be flushwith the apex of the cone or it may extend into the conical region.Thus, the mechanical length of the stub and the length of the opticalfiber can be separated during assembly of the device 210. The conicallyshaped portion of the aperture is sized so as to prevent light energyemanating from the end of the optical fiber 230, or entering it, fromimpinging on the surface of the conically shaped portion of theaperture.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

1. A method of making a device, the method comprising the steps of:selecting a stub having an aperture, the stub having a first end and asecond end, the first end of the stub being separated from the secondend of the stub by a first stub length; forming a portion of theaperture to have a conical shape near the second end of the stub, theconical shape having an apex; inserting an optical fiber into theaperture of the stub; polishing the first end of the stub and a firstend of the optical fiber so as to form a physical contact surfacefinish; selecting a location for a second end of the optical fiberadjacent the apex of the conical portion of the aperture of the stub;terminating the optical fiber so as to form the second end of theoptical fiber, the first end of the optical fiber being separated fromthe second end of the optical fiber by a first optical fiber length, andwherein the first stub length is greater than the first optical fiberlength; and sizing the portion of the aperture having the conical shapeso as to prevent light energy emanating from the second end of theoptical fiber from impinging on a surface of the portion of the aperturehaving the conical shape.
 2. A method of making a device, the methodcomprising the steps of: selecting a stub having an aperture, the stubhaving a first end and a second end, the first end of the stub beingseparated from the second end of the stub by a first stub length;forming a portion of the aperture to have a conical shape near thesecond end of the stub, the conical shape having an apex; applying anadhesive material to at least one of the aperture of the stub and anoptical fiber; inserting the optical fiber into the aperture of the stubso as to affix the optical fiber to the stub by way of the adhesivematerial; polishing the first end of the stub and a first end of theoptical fiber so as to form a physical contact surface finish; selectinga location for a second end of the optical fiber adjacent the apex ofthe conical portion of the aperture of the stub; cleaving the opticalfiber so as to form the second end of the optical fiber, the first endof the optical fiber being separated from the second end of the opticalfiber by a first optical fiber length, and wherein the first stub lengthis greater than the first optical fiber length; and sizing the portionof the aperture having the conical shape so as to prevent light energyemanating from the second end of the optical fiber from impinging on asurface of the portion of the aperture having the conical shape.